Deciding if I like Class D.


I recently purchased Goldenear 1R towers. I was powering them with my Oultlaw 770 initially. I’ve also used a 350 wpc McIntosh a friend owns.. I realize the Outlaw is not audiophile grade, but it’s actually better than most give credit for.  Anyway...

Even though the built in subs are powered, the towers still benifet from a good amount of power, up to 650 rated, so I have been on a quest to find the right amp.

I purchased a set of Hypex Ncore NC1200 Monoblocks with custom buffer boards, and it came with Sparkos 2590s Opamps as per my request. The Goldenears are slightly forward, and I was told Sparkos was the way to go because the were warmer in presentation .

So, I let the amp break in, playing it when I wasn’t home at 85 to 95 DBs for a few days, and gave it some good material to assess it.

I was immediately disenchanted, because the amps sounded very dull, and the highs were rolled off considerably. When compared to the A/B amp the D was not pleasing to my ears. My hearing is slightly diminished from combat, but the A/B was much more detailed.

So I called the company that made amp, and he was very polite and helpful. He sent out a set of Weiss OP2 and Sonic Imagery 990 opamps,to see if I preferred the sound characteristics. Well, the difference was significant.

I am using a Marantz 8805 preamp in pure direct mode . Using BlueOs Streamer, using both optical, and a analog outputs for the testing.. Analog is required to get the MQA files to give full resolution.

To me, the Sparkos just killed the sound. I could honestly see why reviewers would say the treble in particular, was not musical. If I had to live with that sound, I would not..

The Sonic 990 was much better. Much more detailed, better sound stage, just better overall.. Then, I tried the Weiss. Well, that was another level altogether. It sounded like the McIntosh, perhaps better in some regards, but to be honest, it takes a lot time and A-B testing to really be sure. None the less, after hearing the Weiss, it was obvious that they were superior to everything else.

So, I called the manufacturer to let him know my findings, and he said, well, I should give the Sonic 990 another try. I asked why. He said the Weiss would add over 600 dollars for the two pair over the Sparkos and Sonic Imagery.

So, that would bring this setup to over 3100 for the pair. And I could buy a ’good’ high power A/B for that used or even new.

I’ve read a lot of opinions on this forum, and I know the consensus is that D is good, but not great. I know people usually defend what they own, so I needed to hear it for myself. Without a basis of comparison, I’d probably never know the difference, but to be honest, aside from the Hypex getting much louder, and without any audible distortion, I really think the A/B *may* still be more musical, but dammit, I’m not 100% sure. It’s subtle at best.

After hearing the Weiss Opamps, I’d not be satisfied with anything else, but with them, the price is commensurate to A/B.

I’d really appreciate your input on this subject..

BTW, I have purposely left out the company I bought it from, because I think component wise, they are all pretty similar,and I don’t want to start any BS.

I will say though, at the end of the day, the op amps make-or-break the amplifier.

Thank you
Rick




knowitall
the consensus is that D is good, but not great


I find the consensus wrong.  Some Class D amps are better than some Class A.  In general I would avoid making any sort of broad generalizations about Class D based on 1 sample.  Being specific about the amps yields more credible results.

I do agree though, the tropes of Class D having some particular attribute which screams they are switching amps is just not true any more.
I’m with Squires. The "consensus" here is mostly just prejudement.
Speaker/amp match is often a lot more complicated than just class. Like saying blue cars are bad after driving a blue Yugo. 
Holo May DACs must be crap because they are made in China.
@knowitall,


I use my GE Triton Reference speakers with a 300wpc McIntosh MC302 amp.  The sound is totally effortless.  Even before I had the Mac amp, I used a CJ amp and with both amps, the highs were never bright.  I have also owned at 1 time a pair of GE Triton Ones and Triton Twos and never, ever felt any were bright. 
I agree with @erik_squires and @fuzztone on this. Enough so that I won’t repeat their comments here.

My experience with op amps is similar to yours. I much preferred the Sonic Imagery 990ENH TICHA to the Sparkos SS2590 in my setup (Apollon PuriFi-1ET400A-based monoblocks). Good thing, because a friend with Maggies was happy to receive my Sparkos op amps, which suited his ears better in his Class D amps. (As you did, I found the Sparkos a bit rolled off and lacking in detail.)

I have not tried the Weiss op amps; I don’t believe they are plug-compatible with the other two, at least not in my setup. But Daniel Weiss has a superb reputation in high-end pro and home audio.

By the way, I preferred my current Class D amps to some Class AB amps I tried costing 2 to 3 times as much. I could say the Class D amps "perform better" -- they certainly measure better -- but "performance" IMO has become a loaded and almost meaningless concept in high-end audio.

I’m not saying the Goldenear 1Rs are bright, but the Heil like tweeter is certainly more pronounced than most domes, IMHO.. Which is one of the reasons I bought them.

The purpose of this post is to give my opinion, for what it’s worth, on the op amps, and ask if the price tag on the Weiss, which brings the cost over 3000, is worth it or not.. I realize that its personal preference, but it’s not so much the money that concerns me as much as what I’m getting, or could get with it.

BTW, I think the Weiss ought to fit if the others do. Same post positions. 
"...Then, I tried the Weiss. Well, that was another level altogether..."

A few hundred dollars is not much when you get a lifetime of musical enjoyment out of good gear. My suggested upgrade path for you would to upgrade your pre-amp and keep the Op amp you liked. 


The Marantz 8805 is quite good. I don't think that's a factor here.

"...The Marantz 8805 is quite good. I don't think that's a factor here..."

Have you ever tried a high end preamp in your system? 
Post removed 

knowitall OP
I purchased a set of Hypex Ncore NC1200 Monoblocks with custom buffer boards, and it came with Sparkos 2590s Opamps as per my request.
I was immediately disenchanted, because the amps sounded very dull, and the highs were rolled off considerably. When compared to the A/B amp, the D was not pleasing to my ears. My hearing is slightly diminished from combat, but the A/B was much more detailed.


This is probably the reason for what you heard (red trace) with Class-D a massive phase shift starting at 1khz and getting to 70 degrees!! out of phase by 10khz!!! with rapidly increasing distortion (blue trace).
https://ibb.co/3Sg9bZY

All this is put down to the low order output filter, that has to filter out the 600khz switching frequency from the output.

Simple, if the switching frequency was made far higher from 600khz to 1.5mhz as in the (GaN Technics SE-R1), then the output filter can be moved up accordingly 3 x higher along with the "phase shift" and "distortions" and as a result most of those two nasties will then be well out out of the audio band.

Cheers George
If that’s the case George, then why does the op amps make such a significant difference, and in a positive way?


knowitall OPIf that’s the case George, then why does the op amps make such a significant difference, and in a positive way?




All input buffer opamps on the input of Class-D’s have their own sounds. The Hypex NC500 monoblocks (same as Belcanto Reference 600 monos) but with linear power supplies that I also use, I changed and chopped around those input opamps also and got "different" sounds also.
BTW the best sound now from the NC500’s is "no opamps at all", as I can feed my MSB Discrete R2R dac's very high balanced 6v output that has volume control, directly into the NC500’s balanced amplifier stage without having their input opamp buffer stage in the signal path at all.

But they still never get rid of the problem of that phase shift and rising distortion, which to me "sounds like" theirs a different amp from what’s playing the lower part of the music, it’s like there’s a segregation of bass/mids to upper/ mids highs, like two different amps are playing, it’s very listenable still, but not as good as the very best big linear power amps I have.

Cheers George
>> The purpose of this post is to give my opinion . . . and ask if the price tag on the Weiss, which brings the cost over 3000, is worth it or not. <<

As @russ69 said, SURE it’s worth if, given you much prefer the sound.

I’ve bought many components in my 55+ years of audio fever. Not once have I looked back and said: "Oh, I wish I’d bought the cheaper one."

Not that expense is always a marker of value; but when you find something you like and can afford, a delta in the cost is not a big consideration. At least that’s my way of thinking.

P.S. Unless I’m missing something, the detailed spec sheet of the 1ET400A module does not bear out the claims George is making about phase shift and distortion. He may prefer other amps, but that’s a different question.
Well, money is not the issue. As I said, it's what the money gets me that matters. 

George, my Goldenears, as you may know, have a bass section that is powered by its own built in class  D '1600 watt' amp. So the Hypex is basically a line preamp. I'm wondering if perhaps that negates the issue you describe with the phase shift ? Honestly, I'm not sure how that would shake out. 
Post removed 
I’m wondering if perhaps that negates the issue you describe with the phase shift ? Honestly, I’m not sure how that would shake out.
No, because that phase shift starts at 1khz all the way out to 20khz, with increasing distortion. https://ibb.co/3Sg9bZY
It would be akin to an extent to flipping the polarity around on both your tweeters on two way speakers and adding slight distortion, try it and see what you hear, it’ll be either a big hole or a doubling of dB at the xover point

Cheers George
@knowitall


Is it worth it, or what is your current class D amp worth on the used market? If it has value you can live with selling it for, I can highly recommend the LSA Voyager 350 (GaN amp). It's much more authoritative than my EVS 1200 based on IceEdge AS1200 dual mono modules then highly tweaked by Ric Schultz: that surprised me. The Voyager unravels music from many of my CDs that the EVS 1200 could not. This is most likely due to the switching speed

hth
I'm still in the evaluation. with the amps. 
Class D amps do not have the phase shift George claims they do. He’s willfully misreading the wrong measurement.

https://inatinear.blogspot.com/2020/02/class-d-amplifiers-do-not-have-horrible.html

I’ve indirectly measured the phase shift by measuring completed speakers driven by ICEpower amps and it was negligible.

George’s interpretation of this is:

  • Based on misreading of the wrong chart
  • Provably / measurably false
  • He constantly uses it to prove an audible problem only he can hear.
  • One he continues to push despite being corrected by actual amplifier manufacturers



I was not addressing you at all Eric, I’m sure you think your knowitall, but far from it

The real OP knowitall in a PM he sent me, when he started this thread, asked for my opinion, so I gave it to him.

As for you Eric, usually you want to start something, well here ya go.

Class D amps do not have the phase shift George claims they do.
Don’t know why your addressing me, but I need to answer your slanderous **** ****.

Eric knows nothing, I have measured it myself, and it’s confirmed by that graph taken from a test bench measurement product review of it.


George’s interpretation of this is:
  • Based on misreading of the wrong chart
  • Provably / measurably false
  • He constantly uses it to prove an audible problem only he can hear.
  • One he continues to push despite being corrected by actual amplifier manufacturers
Eric again knows nothing, he’s quoted a lofi blogger that also has no idea, he probably coerce him into doing it on his blog, maybe they are related or one in the same.😵



Post removed 

My measurements confirm it.
Here it is once again snapshot taken directly from the Icepower 1200as2 PDF

Clearly states that the "red trace" is the "phase shift" measurement of the amp from 20hz to 20khz!

And the blue trace is rising output impedance/distortion, probably because of diminishing feedback, which will increase distortion.
https://ibb.co/K0HTQ3K
Don’t know why your addressing me,

@georgehifi

Because I am sick of your lies and misappropriation of technical data. I am sick of you bashing anyone who even mentions Class D, not to mention your lack of courtesy and victim blaming. I had thought at least on this ridiculous point using the wrong chart to prove the unproveable you’d felt spanked enough to learn your lesson.

I have measured it myself, and it’s confirmed by that graph taken from a test bench measurement product review of it.


Please show us the product review which shows anything near that graph. The graph you post is directly from B&O / ICEPower and it is not of the output. it is measured across the output filter. Very different thing. If you measured this, then you would be putting your leads somewhere inside the amp module and not the output connectors. The phase shift at the output taps is much lower than you keep quoting and as @atmasphere and others keep telling you in the billions (hyperbole) of previous times you have attempted to use that chart. Given that the same source for your chart has posted both the phase shift at the output filter (irrelevant ) and the phase shift at the actual speaker output you’d think you would switch to using the correct one, but that doesn’t fit with the narrative you keep bashing Class D amps with so you pretend it didn’t happen.

I didn’t post my measurements because they are boring. If you were right, then switching from my Luxman to my ICEpower ASP 250 amps would show significant phase shift using OminiMic, and... they don’t!! The speaker amplitude and phase plots are perfectly normal.
I have T1s and my experience doesn't jive at all with that of the OP.
@knowitall  If I were you I'd give the amp a chance to break in. I know it sounds a bit weird because that module has a lot of feedback and shouldn't need break-in, but our customers have reported this phenomena and we use a similar amount of feedback in our class D module.


As @erik_squires has pointed out, there is quite a lot of difference from one class D amp to another- IME at least as much as you might hear in tube amps. The fact that you so easily hear the differences between the various opamps indicates the module itself is pretty transparent.
there is quite a lot of difference from one class D amp to another


Exactly, so even if one instance of a Class D amp had terrible phase shift problems (and the one George keeps using does not) it would still not be a stand in for all Class D amps.

Further, I’ve played my ICEpower 250 ASP’s for a number of seasoned audiophiles and never has any of them point out anything of what George complains about. He's using the wrong measurement to prove a problem that doesn't exist which only he can hear.
Post removed 
Listened to several as mentioned on,this dead horse subject.
A. A/B, even H is better. Devialet, Rowland, NAD, all this class D is fine, as they are lighter and smaller, but there is something missing, mids, highs, depth of bass kick drum.
If you have concluded D is the best because YOU dumped a huge cash chunk on class D amps, so they must be good.


Really hard to tell if you are serious by such broad statements. Can you give us a specific Class D amp and specific A/B you felt it was inferior to, and exactly by what manner?

BTW, I’m not challenging anyone’s personal experience, but rather that to get to understanding we can’t draw such broad strokes. I can think of a number of Class D and A/B amps that sound better to me than some Class A amps. That doesn’t mean I’m throwing out Class A as inferior, so lets do the same the other way too.

I can also think of some A/B amps that were the equal to some Class D.
“I’ve read a lot of opinions on this forum, and I know the consensus is that D is good, but not great.”

STOP!

Generalizations about Class D are stupid, especially when the opinion is formed based on one or two samples. Even worse are those who express an opinion who have never heard even a single sample. 

Class D is like any other Class / topology. There are good and great and not so great examples of every design approach. I’ve been in this game long enough to have owned many different amplifiers over the years. And although I have owned more tube than SS amps, they all have one thing in common in that they all vary quite a bit even among their own kind, especially in terms of musicality.

Some tube amps, regardless of the tube and topology sound like refuse for the toilet. Same thing with the various SS amps that have passed through my hands over the years. OTOH some were outstanding and some were pretty good. The point is there isn’t any one Class, design approach or topology that is inherently better or more musical than another.
I just read the thread and I see others have already made the same point, so hopefully the above message is clear now.

The measurements and graphs from the manufacturer don't lie Eric, as you are doing and accuse others of doing.

The fact is there plain and simple from the PDF data sheet from the manufacturer themselves, which I also measured to satisfy myself, and if you can't handle that then that's too bad, you need therapy 🤦‍♂️
If you like what you hear, buy the class D. It will most likely be much much more efficient, smaller and lighter to carry around.  Everything else being equal, those are definite advantages. 
Having said that, be aware that if the power supplies are SMPS types, they may be less reliable.  Reputable A/B amps last a long time. I dont quite know about the very long term reliability and longevity of class D's. 
Question is:  Is the best Class D better than the best Class A?

Answer:  No

Rider:  But Class D is a value shortcut and you may get better sound at a relatively low pricepoint.

Rider2:  In this world you rarely get something for nothing.
Question is: Is the best Class D better than the best Class A?

Answer: No

Rider: But Class D is a value shortcut and you may get better sound at a relatively low pricepoint.
Price is not the only reason to consider class D. Class D offers some advantages to the designer- for example, the distortion the amp makes is not dependent on the output section. Its generated in very different ways and so has a different distortion signature than traditional solid state (which tends to be bright).


How designers take advantage of this fact varies tremendously from amp to amp. A lot is in the execution. As a result a blanket statement such as seen in the quote above is likely false- the correct 'Answer:' is 'It depends.'